1 //===-- llvm/Support/MathExtras.h - Useful math functions -------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file contains some functions that are useful for math stuff. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_SUPPORT_MATHEXTRAS_H 15 #define LLVM_SUPPORT_MATHEXTRAS_H 16 17 #include "llvm/Support/Compiler.h" 18 #include "llvm/Support/SwapByteOrder.h" 19 #include <cassert> 20 #include <cstring> 21 #include <type_traits> 22 23 #ifdef _MSC_VER 24 #include <intrin.h> 25 #include <limits> 26 #endif 27 28 namespace llvm { 29 /// \brief The behavior an operation has on an input of 0. 30 enum ZeroBehavior { 31 /// \brief The returned value is undefined. 32 ZB_Undefined, 33 /// \brief The returned value is numeric_limits<T>::max() 34 ZB_Max, 35 /// \brief The returned value is numeric_limits<T>::digits 36 ZB_Width 37 }; 38 39 /// \brief Count number of 0's from the least significant bit to the most 40 /// stopping at the first 1. 41 /// 42 /// Only unsigned integral types are allowed. 43 /// 44 /// \param ZB the behavior on an input of 0. Only ZB_Width and ZB_Undefined are 45 /// valid arguments. 46 template <typename T> 47 typename std::enable_if<std::numeric_limits<T>::is_integer && 48 !std::numeric_limits<T>::is_signed, std::size_t>::type 49 countTrailingZeros(T Val, ZeroBehavior ZB = ZB_Width) { 50 (void)ZB; 51 52 if (!Val) 53 return std::numeric_limits<T>::digits; 54 if (Val & 0x1) 55 return 0; 56 57 // Bisection method. 58 std::size_t ZeroBits = 0; 59 T Shift = std::numeric_limits<T>::digits >> 1; 60 T Mask = std::numeric_limits<T>::max() >> Shift; 61 while (Shift) { 62 if ((Val & Mask) == 0) { 63 Val >>= Shift; 64 ZeroBits |= Shift; 65 } 66 Shift >>= 1; 67 Mask >>= Shift; 68 } 69 return ZeroBits; 70 } 71 72 // Disable signed. 73 template <typename T> 74 typename std::enable_if<std::numeric_limits<T>::is_integer && 75 std::numeric_limits<T>::is_signed, std::size_t>::type 76 countTrailingZeros(T Val, ZeroBehavior ZB = ZB_Width) LLVM_DELETED_FUNCTION; 77 78 #if __GNUC__ >= 4 || _MSC_VER 79 template <> 80 inline std::size_t countTrailingZeros<uint32_t>(uint32_t Val, ZeroBehavior ZB) { 81 if (ZB != ZB_Undefined && Val == 0) 82 return 32; 83 84 #if __has_builtin(__builtin_ctz) || __GNUC_PREREQ(4, 0) 85 return __builtin_ctz(Val); 86 #elif _MSC_VER 87 unsigned long Index; 88 _BitScanForward(&Index, Val); 89 return Index; 90 #endif 91 } 92 93 #if !defined(_MSC_VER) || defined(_M_X64) 94 template <> 95 inline std::size_t countTrailingZeros<uint64_t>(uint64_t Val, ZeroBehavior ZB) { 96 if (ZB != ZB_Undefined && Val == 0) 97 return 64; 98 99 #if __has_builtin(__builtin_ctzll) || __GNUC_PREREQ(4, 0) 100 return __builtin_ctzll(Val); 101 #elif _MSC_VER 102 unsigned long Index; 103 _BitScanForward64(&Index, Val); 104 return Index; 105 #endif 106 } 107 #endif 108 #endif 109 110 /// \brief Count number of 0's from the most significant bit to the least 111 /// stopping at the first 1. 112 /// 113 /// Only unsigned integral types are allowed. 114 /// 115 /// \param ZB the behavior on an input of 0. Only ZB_Width and ZB_Undefined are 116 /// valid arguments. 117 template <typename T> 118 typename std::enable_if<std::numeric_limits<T>::is_integer && 119 !std::numeric_limits<T>::is_signed, std::size_t>::type 120 countLeadingZeros(T Val, ZeroBehavior ZB = ZB_Width) { 121 (void)ZB; 122 123 if (!Val) 124 return std::numeric_limits<T>::digits; 125 126 // Bisection method. 127 std::size_t ZeroBits = 0; 128 for (T Shift = std::numeric_limits<T>::digits >> 1; Shift; Shift >>= 1) { 129 T Tmp = Val >> Shift; 130 if (Tmp) 131 Val = Tmp; 132 else 133 ZeroBits |= Shift; 134 } 135 return ZeroBits; 136 } 137 138 // Disable signed. 139 template <typename T> 140 typename std::enable_if<std::numeric_limits<T>::is_integer && 141 std::numeric_limits<T>::is_signed, std::size_t>::type 142 countLeadingZeros(T Val, ZeroBehavior ZB = ZB_Width) LLVM_DELETED_FUNCTION; 143 144 #if __GNUC__ >= 4 || _MSC_VER 145 template <> 146 inline std::size_t countLeadingZeros<uint32_t>(uint32_t Val, ZeroBehavior ZB) { 147 if (ZB != ZB_Undefined && Val == 0) 148 return 32; 149 150 #if __has_builtin(__builtin_clz) || __GNUC_PREREQ(4, 0) 151 return __builtin_clz(Val); 152 #elif _MSC_VER 153 unsigned long Index; 154 _BitScanReverse(&Index, Val); 155 return Index ^ 31; 156 #endif 157 } 158 159 #if !defined(_MSC_VER) || defined(_M_X64) 160 template <> 161 inline std::size_t countLeadingZeros<uint64_t>(uint64_t Val, ZeroBehavior ZB) { 162 if (ZB != ZB_Undefined && Val == 0) 163 return 64; 164 165 #if __has_builtin(__builtin_clzll) || __GNUC_PREREQ(4, 0) 166 return __builtin_clzll(Val); 167 #elif _MSC_VER 168 unsigned long Index; 169 _BitScanReverse64(&Index, Val); 170 return Index ^ 63; 171 #endif 172 } 173 #endif 174 #endif 175 176 /// \brief Get the index of the first set bit starting from the least 177 /// significant bit. 178 /// 179 /// Only unsigned integral types are allowed. 180 /// 181 /// \param ZB the behavior on an input of 0. Only ZB_Max and ZB_Undefined are 182 /// valid arguments. 183 template <typename T> 184 typename std::enable_if<std::numeric_limits<T>::is_integer && 185 !std::numeric_limits<T>::is_signed, T>::type 186 findFirstSet(T Val, ZeroBehavior ZB = ZB_Max) { 187 if (ZB == ZB_Max && Val == 0) 188 return std::numeric_limits<T>::max(); 189 190 return countTrailingZeros(Val, ZB_Undefined); 191 } 192 193 // Disable signed. 194 template <typename T> 195 typename std::enable_if<std::numeric_limits<T>::is_integer && 196 std::numeric_limits<T>::is_signed, T>::type 197 findFirstSet(T Val, ZeroBehavior ZB = ZB_Max) LLVM_DELETED_FUNCTION; 198 199 /// \brief Get the index of the last set bit starting from the least 200 /// significant bit. 201 /// 202 /// Only unsigned integral types are allowed. 203 /// 204 /// \param ZB the behavior on an input of 0. Only ZB_Max and ZB_Undefined are 205 /// valid arguments. 206 template <typename T> 207 typename std::enable_if<std::numeric_limits<T>::is_integer && 208 !std::numeric_limits<T>::is_signed, T>::type 209 findLastSet(T Val, ZeroBehavior ZB = ZB_Max) { 210 if (ZB == ZB_Max && Val == 0) 211 return std::numeric_limits<T>::max(); 212 213 // Use ^ instead of - because both gcc and llvm can remove the associated ^ 214 // in the __builtin_clz intrinsic on x86. 215 return countLeadingZeros(Val, ZB_Undefined) ^ 216 (std::numeric_limits<T>::digits - 1); 217 } 218 219 // Disable signed. 220 template <typename T> 221 typename std::enable_if<std::numeric_limits<T>::is_integer && 222 std::numeric_limits<T>::is_signed, T>::type 223 findLastSet(T Val, ZeroBehavior ZB = ZB_Max) LLVM_DELETED_FUNCTION; 224 225 /// \brief Macro compressed bit reversal table for 256 bits. 226 /// 227 /// http://graphics.stanford.edu/~seander/bithacks.html#BitReverseTable 228 static const unsigned char BitReverseTable256[256] = { 229 #define R2(n) n, n + 2 * 64, n + 1 * 64, n + 3 * 64 230 #define R4(n) R2(n), R2(n + 2 * 16), R2(n + 1 * 16), R2(n + 3 * 16) 231 #define R6(n) R4(n), R4(n + 2 * 4), R4(n + 1 * 4), R4(n + 3 * 4) 232 R6(0), R6(2), R6(1), R6(3) 233 #undef R2 234 #undef R4 235 #undef R6 236 }; 237 238 /// \brief Reverse the bits in \p Val. 239 template <typename T> 240 T reverseBits(T Val) { 241 unsigned char in[sizeof(Val)]; 242 unsigned char out[sizeof(Val)]; 243 std::memcpy(in, &Val, sizeof(Val)); 244 for (unsigned i = 0; i < sizeof(Val); ++i) 245 out[(sizeof(Val) - i) - 1] = BitReverseTable256[in[i]]; 246 std::memcpy(&Val, out, sizeof(Val)); 247 return Val; 248 } 249 250 // NOTE: The following support functions use the _32/_64 extensions instead of 251 // type overloading so that signed and unsigned integers can be used without 252 // ambiguity. 253 254 /// Hi_32 - This function returns the high 32 bits of a 64 bit value. 255 inline uint32_t Hi_32(uint64_t Value) { 256 return static_cast<uint32_t>(Value >> 32); 257 } 258 259 /// Lo_32 - This function returns the low 32 bits of a 64 bit value. 260 inline uint32_t Lo_32(uint64_t Value) { 261 return static_cast<uint32_t>(Value); 262 } 263 264 /// Make_64 - This functions makes a 64-bit integer from a high / low pair of 265 /// 32-bit integers. 266 inline uint64_t Make_64(uint32_t High, uint32_t Low) { 267 return ((uint64_t)High << 32) | (uint64_t)Low; 268 } 269 270 /// isInt - Checks if an integer fits into the given bit width. 271 template<unsigned N> 272 inline bool isInt(int64_t x) { 273 return N >= 64 || (-(INT64_C(1)<<(N-1)) <= x && x < (INT64_C(1)<<(N-1))); 274 } 275 // Template specializations to get better code for common cases. 276 template<> 277 inline bool isInt<8>(int64_t x) { 278 return static_cast<int8_t>(x) == x; 279 } 280 template<> 281 inline bool isInt<16>(int64_t x) { 282 return static_cast<int16_t>(x) == x; 283 } 284 template<> 285 inline bool isInt<32>(int64_t x) { 286 return static_cast<int32_t>(x) == x; 287 } 288 289 /// isShiftedInt<N,S> - Checks if a signed integer is an N bit number shifted 290 /// left by S. 291 template<unsigned N, unsigned S> 292 inline bool isShiftedInt(int64_t x) { 293 return isInt<N+S>(x) && (x % (1<<S) == 0); 294 } 295 296 /// isUInt - Checks if an unsigned integer fits into the given bit width. 297 template<unsigned N> 298 inline bool isUInt(uint64_t x) { 299 return N >= 64 || x < (UINT64_C(1)<<(N)); 300 } 301 // Template specializations to get better code for common cases. 302 template<> 303 inline bool isUInt<8>(uint64_t x) { 304 return static_cast<uint8_t>(x) == x; 305 } 306 template<> 307 inline bool isUInt<16>(uint64_t x) { 308 return static_cast<uint16_t>(x) == x; 309 } 310 template<> 311 inline bool isUInt<32>(uint64_t x) { 312 return static_cast<uint32_t>(x) == x; 313 } 314 315 /// isShiftedUInt<N,S> - Checks if a unsigned integer is an N bit number shifted 316 /// left by S. 317 template<unsigned N, unsigned S> 318 inline bool isShiftedUInt(uint64_t x) { 319 return isUInt<N+S>(x) && (x % (1<<S) == 0); 320 } 321 322 /// isUIntN - Checks if an unsigned integer fits into the given (dynamic) 323 /// bit width. 324 inline bool isUIntN(unsigned N, uint64_t x) { 325 return x == (x & (~0ULL >> (64 - N))); 326 } 327 328 /// isIntN - Checks if an signed integer fits into the given (dynamic) 329 /// bit width. 330 inline bool isIntN(unsigned N, int64_t x) { 331 return N >= 64 || (-(INT64_C(1)<<(N-1)) <= x && x < (INT64_C(1)<<(N-1))); 332 } 333 334 /// isMask_32 - This function returns true if the argument is a sequence of ones 335 /// starting at the least significant bit with the remainder zero (32 bit 336 /// version). Ex. isMask_32(0x0000FFFFU) == true. 337 inline bool isMask_32(uint32_t Value) { 338 return Value && ((Value + 1) & Value) == 0; 339 } 340 341 /// isMask_64 - This function returns true if the argument is a sequence of ones 342 /// starting at the least significant bit with the remainder zero (64 bit 343 /// version). 344 inline bool isMask_64(uint64_t Value) { 345 return Value && ((Value + 1) & Value) == 0; 346 } 347 348 /// isShiftedMask_32 - This function returns true if the argument contains a 349 /// sequence of ones with the remainder zero (32 bit version.) 350 /// Ex. isShiftedMask_32(0x0000FF00U) == true. 351 inline bool isShiftedMask_32(uint32_t Value) { 352 return isMask_32((Value - 1) | Value); 353 } 354 355 /// isShiftedMask_64 - This function returns true if the argument contains a 356 /// sequence of ones with the remainder zero (64 bit version.) 357 inline bool isShiftedMask_64(uint64_t Value) { 358 return isMask_64((Value - 1) | Value); 359 } 360 361 /// isPowerOf2_32 - This function returns true if the argument is a power of 362 /// two > 0. Ex. isPowerOf2_32(0x00100000U) == true (32 bit edition.) 363 inline bool isPowerOf2_32(uint32_t Value) { 364 return Value && !(Value & (Value - 1)); 365 } 366 367 /// isPowerOf2_64 - This function returns true if the argument is a power of two 368 /// > 0 (64 bit edition.) 369 inline bool isPowerOf2_64(uint64_t Value) { 370 return Value && !(Value & (Value - int64_t(1L))); 371 } 372 373 /// ByteSwap_16 - This function returns a byte-swapped representation of the 374 /// 16-bit argument, Value. 375 inline uint16_t ByteSwap_16(uint16_t Value) { 376 return sys::SwapByteOrder_16(Value); 377 } 378 379 /// ByteSwap_32 - This function returns a byte-swapped representation of the 380 /// 32-bit argument, Value. 381 inline uint32_t ByteSwap_32(uint32_t Value) { 382 return sys::SwapByteOrder_32(Value); 383 } 384 385 /// ByteSwap_64 - This function returns a byte-swapped representation of the 386 /// 64-bit argument, Value. 387 inline uint64_t ByteSwap_64(uint64_t Value) { 388 return sys::SwapByteOrder_64(Value); 389 } 390 391 /// CountLeadingOnes_32 - this function performs the operation of 392 /// counting the number of ones from the most significant bit to the first zero 393 /// bit. Ex. CountLeadingOnes_32(0xFF0FFF00) == 8. 394 /// Returns 32 if the word is all ones. 395 inline unsigned CountLeadingOnes_32(uint32_t Value) { 396 return countLeadingZeros(~Value); 397 } 398 399 /// CountLeadingOnes_64 - This function performs the operation 400 /// of counting the number of ones from the most significant bit to the first 401 /// zero bit (64 bit edition.) 402 /// Returns 64 if the word is all ones. 403 inline unsigned CountLeadingOnes_64(uint64_t Value) { 404 return countLeadingZeros(~Value); 405 } 406 407 /// CountTrailingOnes_32 - this function performs the operation of 408 /// counting the number of ones from the least significant bit to the first zero 409 /// bit. Ex. CountTrailingOnes_32(0x00FF00FF) == 8. 410 /// Returns 32 if the word is all ones. 411 inline unsigned CountTrailingOnes_32(uint32_t Value) { 412 return countTrailingZeros(~Value); 413 } 414 415 /// CountTrailingOnes_64 - This function performs the operation 416 /// of counting the number of ones from the least significant bit to the first 417 /// zero bit (64 bit edition.) 418 /// Returns 64 if the word is all ones. 419 inline unsigned CountTrailingOnes_64(uint64_t Value) { 420 return countTrailingZeros(~Value); 421 } 422 423 /// CountPopulation_32 - this function counts the number of set bits in a value. 424 /// Ex. CountPopulation(0xF000F000) = 8 425 /// Returns 0 if the word is zero. 426 inline unsigned CountPopulation_32(uint32_t Value) { 427 #if __GNUC__ >= 4 428 return __builtin_popcount(Value); 429 #else 430 uint32_t v = Value - ((Value >> 1) & 0x55555555); 431 v = (v & 0x33333333) + ((v >> 2) & 0x33333333); 432 return ((v + (v >> 4) & 0xF0F0F0F) * 0x1010101) >> 24; 433 #endif 434 } 435 436 /// CountPopulation_64 - this function counts the number of set bits in a value, 437 /// (64 bit edition.) 438 inline unsigned CountPopulation_64(uint64_t Value) { 439 #if __GNUC__ >= 4 440 return __builtin_popcountll(Value); 441 #else 442 uint64_t v = Value - ((Value >> 1) & 0x5555555555555555ULL); 443 v = (v & 0x3333333333333333ULL) + ((v >> 2) & 0x3333333333333333ULL); 444 v = (v + (v >> 4)) & 0x0F0F0F0F0F0F0F0FULL; 445 return unsigned((uint64_t)(v * 0x0101010101010101ULL) >> 56); 446 #endif 447 } 448 449 /// Log2_32 - This function returns the floor log base 2 of the specified value, 450 /// -1 if the value is zero. (32 bit edition.) 451 /// Ex. Log2_32(32) == 5, Log2_32(1) == 0, Log2_32(0) == -1, Log2_32(6) == 2 452 inline unsigned Log2_32(uint32_t Value) { 453 return 31 - countLeadingZeros(Value); 454 } 455 456 /// Log2_64 - This function returns the floor log base 2 of the specified value, 457 /// -1 if the value is zero. (64 bit edition.) 458 inline unsigned Log2_64(uint64_t Value) { 459 return 63 - countLeadingZeros(Value); 460 } 461 462 /// Log2_32_Ceil - This function returns the ceil log base 2 of the specified 463 /// value, 32 if the value is zero. (32 bit edition). 464 /// Ex. Log2_32_Ceil(32) == 5, Log2_32_Ceil(1) == 0, Log2_32_Ceil(6) == 3 465 inline unsigned Log2_32_Ceil(uint32_t Value) { 466 return 32 - countLeadingZeros(Value - 1); 467 } 468 469 /// Log2_64_Ceil - This function returns the ceil log base 2 of the specified 470 /// value, 64 if the value is zero. (64 bit edition.) 471 inline unsigned Log2_64_Ceil(uint64_t Value) { 472 return 64 - countLeadingZeros(Value - 1); 473 } 474 475 /// GreatestCommonDivisor64 - Return the greatest common divisor of the two 476 /// values using Euclid's algorithm. 477 inline uint64_t GreatestCommonDivisor64(uint64_t A, uint64_t B) { 478 while (B) { 479 uint64_t T = B; 480 B = A % B; 481 A = T; 482 } 483 return A; 484 } 485 486 /// BitsToDouble - This function takes a 64-bit integer and returns the bit 487 /// equivalent double. 488 inline double BitsToDouble(uint64_t Bits) { 489 union { 490 uint64_t L; 491 double D; 492 } T; 493 T.L = Bits; 494 return T.D; 495 } 496 497 /// BitsToFloat - This function takes a 32-bit integer and returns the bit 498 /// equivalent float. 499 inline float BitsToFloat(uint32_t Bits) { 500 union { 501 uint32_t I; 502 float F; 503 } T; 504 T.I = Bits; 505 return T.F; 506 } 507 508 /// DoubleToBits - This function takes a double and returns the bit 509 /// equivalent 64-bit integer. Note that copying doubles around 510 /// changes the bits of NaNs on some hosts, notably x86, so this 511 /// routine cannot be used if these bits are needed. 512 inline uint64_t DoubleToBits(double Double) { 513 union { 514 uint64_t L; 515 double D; 516 } T; 517 T.D = Double; 518 return T.L; 519 } 520 521 /// FloatToBits - This function takes a float and returns the bit 522 /// equivalent 32-bit integer. Note that copying floats around 523 /// changes the bits of NaNs on some hosts, notably x86, so this 524 /// routine cannot be used if these bits are needed. 525 inline uint32_t FloatToBits(float Float) { 526 union { 527 uint32_t I; 528 float F; 529 } T; 530 T.F = Float; 531 return T.I; 532 } 533 534 /// Platform-independent wrappers for the C99 isnan() function. 535 int IsNAN(float f); 536 int IsNAN(double d); 537 538 /// Platform-independent wrappers for the C99 isinf() function. 539 int IsInf(float f); 540 int IsInf(double d); 541 542 /// MinAlign - A and B are either alignments or offsets. Return the minimum 543 /// alignment that may be assumed after adding the two together. 544 inline uint64_t MinAlign(uint64_t A, uint64_t B) { 545 // The largest power of 2 that divides both A and B. 546 // 547 // Replace "-Value" by "1+~Value" in the following commented code to avoid 548 // MSVC warning C4146 549 // return (A | B) & -(A | B); 550 return (A | B) & (1 + ~(A | B)); 551 } 552 553 /// \brief Aligns \c Ptr to \c Alignment bytes, rounding up. 554 /// 555 /// Alignment should be a power of two. This method rounds up, so 556 /// AlignPtr(7, 4) == 8 and AlignPtr(8, 4) == 8. 557 inline char *alignPtr(char *Ptr, size_t Alignment) { 558 assert(Alignment && isPowerOf2_64((uint64_t)Alignment) && 559 "Alignment is not a power of two!"); 560 561 return (char *)(((uintptr_t)Ptr + Alignment - 1) & 562 ~(uintptr_t)(Alignment - 1)); 563 } 564 565 /// NextPowerOf2 - Returns the next power of two (in 64-bits) 566 /// that is strictly greater than A. Returns zero on overflow. 567 inline uint64_t NextPowerOf2(uint64_t A) { 568 A |= (A >> 1); 569 A |= (A >> 2); 570 A |= (A >> 4); 571 A |= (A >> 8); 572 A |= (A >> 16); 573 A |= (A >> 32); 574 return A + 1; 575 } 576 577 /// Returns the power of two which is less than or equal to the given value. 578 /// Essentially, it is a floor operation across the domain of powers of two. 579 inline uint64_t PowerOf2Floor(uint64_t A) { 580 if (!A) return 0; 581 return 1ull << (63 - countLeadingZeros(A, ZB_Undefined)); 582 } 583 584 /// Returns the next integer (mod 2**64) that is greater than or equal to 585 /// \p Value and is a multiple of \p Align. \p Align must be non-zero. 586 /// 587 /// Examples: 588 /// \code 589 /// RoundUpToAlignment(5, 8) = 8 590 /// RoundUpToAlignment(17, 8) = 24 591 /// RoundUpToAlignment(~0LL, 8) = 0 592 /// \endcode 593 inline uint64_t RoundUpToAlignment(uint64_t Value, uint64_t Align) { 594 return ((Value + Align - 1) / Align) * Align; 595 } 596 597 /// Returns the offset to the next integer (mod 2**64) that is greater than 598 /// or equal to \p Value and is a multiple of \p Align. \p Align must be 599 /// non-zero. 600 inline uint64_t OffsetToAlignment(uint64_t Value, uint64_t Align) { 601 return RoundUpToAlignment(Value, Align) - Value; 602 } 603 604 /// abs64 - absolute value of a 64-bit int. Not all environments support 605 /// "abs" on whatever their name for the 64-bit int type is. The absolute 606 /// value of the largest negative number is undefined, as with "abs". 607 inline int64_t abs64(int64_t x) { 608 return (x < 0) ? -x : x; 609 } 610 611 /// SignExtend32 - Sign extend B-bit number x to 32-bit int. 612 /// Usage int32_t r = SignExtend32<5>(x); 613 template <unsigned B> inline int32_t SignExtend32(uint32_t x) { 614 return int32_t(x << (32 - B)) >> (32 - B); 615 } 616 617 /// \brief Sign extend number in the bottom B bits of X to a 32-bit int. 618 /// Requires 0 < B <= 32. 619 inline int32_t SignExtend32(uint32_t X, unsigned B) { 620 return int32_t(X << (32 - B)) >> (32 - B); 621 } 622 623 /// SignExtend64 - Sign extend B-bit number x to 64-bit int. 624 /// Usage int64_t r = SignExtend64<5>(x); 625 template <unsigned B> inline int64_t SignExtend64(uint64_t x) { 626 return int64_t(x << (64 - B)) >> (64 - B); 627 } 628 629 /// \brief Sign extend number in the bottom B bits of X to a 64-bit int. 630 /// Requires 0 < B <= 64. 631 inline int64_t SignExtend64(uint64_t X, unsigned B) { 632 return int64_t(X << (64 - B)) >> (64 - B); 633 } 634 635 #if defined(_MSC_VER) 636 // Visual Studio defines the HUGE_VAL class of macros using purposeful 637 // constant arithmetic overflow, which it then warns on when encountered. 638 const float huge_valf = std::numeric_limits<float>::infinity(); 639 #else 640 const float huge_valf = HUGE_VALF; 641 #endif 642 } // End llvm namespace 643 644 #endif 645